xen/pvcalls: use GFP_ATOMIC under spin lock

A spin lock is taken here so we should use GFP_ATOMIC.

Fixes: 9774c6cca266 ("xen/pvcalls: implement accept command")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
index d1e1d8d..4c789e6 100644
--- a/drivers/xen/pvcalls-front.c
+++ b/drivers/xen/pvcalls-front.c
@@ -805,7 +805,7 @@
 		pvcalls_exit();
 		return ret;
 	}
-	map2 = kzalloc(sizeof(*map2), GFP_KERNEL);
+	map2 = kzalloc(sizeof(*map2), GFP_ATOMIC);
 	if (map2 == NULL) {
 		clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
 			  (void *)&map->passive.flags);